US2187250A

US2187250A - Method of compensating for roll deflection

Info

Publication number: US2187250A
Application number: US168318A
Authority: US
Inventors: Sendzimir Tadems
Original assignee: American Rolling Mill Co
Current assignee: American Rolling Mill Co
Priority date: 1936-10-16
Filing date: 1937-10-11
Publication date: 1940-01-16
Anticipated expiration: 1957-01-16
Also published as: FR856965A; BE435233A; DE698450C; GB529735A

Description

M 1940- 'r. SENDZIMIR 2,187,250

IBTHOD OP COIPENSATXNG FOR ROLL DEFLICTION Filed Oct. 11, 1937 2 Sheets-Sheet 1 INVENTOR.

Dan/a2 SENDZ/MIR.

ATTORNEY!- Jan. 16, 1940.

T. SENDZIMIR IETHOD 0F COIPENSATING FOR ROLL DEFLEC'I'ION Filed Oct. 11, 1937 FIG-Z 2 Sheets-Sheet 2 INVENTOR. Thazusz SENDZ/M/R.

ATTORNEYS.

Patented Jan. 16,1940

IIIIOD OI OOWSATING FOB ROI]:

. DIRECTION Tadensa Sendsimir,

rarhrranoaamlgnorto'lhe lllddletowll.

American Bolling Hill Company, Ohio, a corporation ol Ohio Application October 11, 1987, Serial No. 168,818

- In Germany October 15. 1086 i2 Claims. (CL 8H8) My invention relates to rolling mills and more particularly to a method of compensating the deflection in the working rolls or in the mill housing, caused by rolling operation. Bald deflection 5 causes the stretching of the metal to be not uniform throughout the width of the sheet.

, It has been proposed to overcome this well known phenomena. by shaping the working rolls in such a way as to give them a certain crown 19 (that means giving them a larger size in the middle than at the ends) and thus obtain a certain regularity of the rollclearance for a certain sag. It is, however, obvious that such a way of overcoming irregularities in the gauge of the strip throughout its width is only good for a certain roll pressure, that means for a given hardness, a given reduction and a given width of the metal to be rolled. It is sufllcient for one of these factors changing slightly, to disturb the equilibrium between the crown and the sex, the roll gap losing its regularity.

For instance, if one end of a sheet to be rolled is at a lower temperature than the other, the roll pressure will rise and a sheet with waves on both sides is 'the result.

The same difliculties are encountered if dealing with metal of irregular thickness or hardness. My invention is to overcome all these difliculties and make the elongation caused by the working that irrespectively of the roll pressure, as will be explained in the following description with reference to the figures, of which: Fig.1 is a longitudinal section of a working, or supporting roll, showing my compensating means.

Fig. 2 is a modification of same.

Fig. 3 is a section along'the axis KY of Fig. 2.

Fig. 4 is a working or supporting roll with a still further modification of my compensating feature.

Fig. 5 is .a section along the axis WZ of Fig. 4.

Fig. 6 is a transversal section along A B of Fig. '7 of a sir: high mill in which each working roll is back by two series of backing rollers supported y two parallel beams, said beams being compensated according to my invention.

Fig. 'I is thesame in plansection.

Fig. 8 is a perspective of the same.

Fig. 9 is a cross section representing a feature of: my invention applied to a mill similar to the one of Fig. 6, but in which the working rolls are backed by backing rolls, said backing rolls supported by a set of supporting rollers, supported in their turn by two parallel beams compensated rolls equal throughout their entire length andaccording to my invention-in a somewhat modified W88.

Fig. 10 is a longitudinal section of a further modification of the same feature, especially applicable to supporting rolls.

Fig. l representsa working roll, such as used for rolling of metal sheets, comprising a steel shaft i and a special steel alloy shell 3, mounted upon it; said shaft is crown shaped and the clearance between the interior of the shell and the exterior of the shaft is filled up by metal or alloy 2, such as cast iron, for instance, having a relatively smaller modulus of elasticity.

The shape of the clearance is such, that the intermediate metal or alloy 2 has a greater thickness at the ends of the roll than in the middle. The effect such a composite compensating roll has on the sheet of metal being rolled and more particularly the amount of elongation or stretching, which is caused by the part of the roll situated near its centre, as compared with the ends of the rolls,(corresponding to the middle and the sides of the sheet respectively) will depend on the elastic deflection of the outer shell, at each point of contact with the rolled metal. First of all,'all the three parts (I, I, 3) of the composite roll will deflect under the more or less uniform load of the rolling pressure and the sag of this deflection will be biggest in the middle.

Secondly, and in addition to the first named deflection, the outer shell will deflect and also will become flattened, at the point of contact with'the metal to be rolled. The amount of such deflection and of such flattening (which are two entirely independent values) will depend upon the elastic characteristics of the materials of the three and particularly of the other two parts (2, I) and the form or thickness of the less elastic shell 3 and the more elastic inner core 2. when we want to analyse the sag and flattening of this shell 3, caused by the rolling pressure, independently of the first named sag oi the whole roll,

including its shaft I, it is best to consider forthe moment this shaft i as ideally rigid, that is giving no sag whatever under the influence of the rolling pressure. On this assumption it is evident by looking at Fig. 1 that both the deflection of the outer shell 3, when considered as a whole body, as well as its flattening at the point of contact with the metal sheet being rolled (where the pressure is applied to the roll) will be higher at or near both ends than in the centre of the roll. This is due to the fact that an additional sag is artificially introduced, due to the replacement of those parts of the roll, indicated compensate for the natural pressure which is always greatest in the centre and smallest at the ends.

By a suitable proportioning of the three parts of the rolls (I, 2, 3) and by the proper choice of the materials of a suitable elasticity, especially of the part 2, as there is not much choice for the materials ofthe parts I and I, a roll can be obtained that will stretch metal sheets uniformly at the sides and in the centre, irrespective of the rolling pressure applied. That is to say, that a strip may be rolled at, for instance, 25% reduction,'the reduction may then be increased, for instance, to 40% and yet the strip will remain flat. As against this, with ordinary rolls, with a crown suitable for such a 25% reduction and producing a flat strip at such reduction, when the pressure is increased to obtain a 40% reduction. the sag of the rolls increases and a strip is produced which has waves at both sides. The same Ithing happens when a strip is not uniform in heat, thickness, temper etc. All such changes alter the roll pressure and the difl'erence in roll sag which results from it, is responsible for the production of a sheet or strip which is not flat, but wavyat the sides (when the rolling pressure increases) or at the centre (when it decreases). It must be especially emphasised that this invention does not exclude the grinding of the rolls togivethemacertaincrowmthatcanbeused combined with my compensating means; and when a certain crown produces a flat sheet at 10% reduction. with a correctly designed roll.

as per this invention, it will also produce a flat sheet when rolling with a 20% or 30% reduction or more, within the iimitsto which a roll may be loaded,'which are necessarily within the limits of elasticity of the materials, so that the various deflections and sags are proportional to the stretches or loads.

The point is to correctly proportion the different thicknesses and the elasticities of the different materials used in my combined rolls, so as to make the roll work regularly throughout all its length. Thus the differences of reduction and temperature of the metal to be rolled have no,

influence in what concerns the regularity of the roll taglap and therefore the thickness of the rolled me Figs. 2 and 3 show another embodiment of the same principle in which the working or supporting rolls are made of one piece of metal. The

weaker or more flexible zone of the roll is obtainedby removing a part of the metal, as by providing a series of concentrically disposed holes, the depth, size and number of which is calculated in view of obtaining the mentioned result.

Figs. 4 and 5 illustrate still another form which is specially recommended when rolling on a two high mill. The shell 2 in this instance is more thin and its flattening eflect, at the point of contact with the metal being rolled, and the correspondingly diminished stretching power of the roll at places where such flattening is bigger, is

relied upon to compensate for the natural sag of the roll. The zone of higher compressibility 2 which must of course be either deeper, or more elastic, or both, near the sides of the core or shaft of the roll I where some-proportion of the metal is removed at frequent intervals, as by providing slots 2 where such metal is removed,

' arsmso the remaining metal is subject to bigger stresses and .corresponding yields, or is compressed more than it it were continuous.

For back or intermediate rolls such as 22 in Figure 9 which are backed up along their whole length, the composite deflection (that is the deflection of working and intermediate rolls plus the deflection of the backing members) may be corrected by simply making such rolls hollow, the diameter of the hole increasing toward the ends (Fig. 10). Such a roll, being pressed on three sides as shown in Figure 9 will sag along its cross-section, adopting a somewhat triangular shape in section. The wall thickness of the roll being variable owing to the shape of the hole therein, the sag will vary in different places along the axis of the roll. Thus, by suitably shaping the hole or hollow in the roll, the sag may be made such as to compensate for the natural sag of the working roll.

Figs. 6, 7, 8 refer to another feature of my invention and that is to bring the said compensating eflect unto the supporting members of a six high mill, more particularly on the horizontal beams ll of the mill housing. The working rolls l2 are backed by rings l3, said rings being rotatively mounted (as on roller bearings) on shafts I. Said shafts H are supported by suitable bearings It, said bearings being directly mounted in the horizontal cross members, as H of the housing. For this eifect, in the horizontal beams I l suitable bores are provided, in which the bearings it are inserted and preferably disposed in quincunx, as clearly shown on Fig. 7. As shown in Fig. 6 the components 32 and a of the roll pressure 2i act upon lateral lips or flanges I! of the horizontal beams ll, so as to force them sideways a certain small distance. Thus the deflection of the roll I2 is the vectorial sum of the vertical deflection of the beams II and the transversal deflection of the flanges It.

The last named deflection will be equal throughout the whole length of the flanges, as long as they are independent at their ends, as at IT, Fig. 7. The deflection of the beams II is maximum in the middle of their length. In order to compensate that maximum deflection I reduce the thickness on the lips It at their ends, so as to make them weaker on the sides than in the middle as it is seen on Figs. 6, '7 and 8. Clamps 24 (Figs. 6 and '7) may be provided to re-inforce said lips II at certain places, such re-inforcement being adjustable by tightening the corresponding bolts. Such clamps may be necessary to correct the compensating eifect on mills which have not been correctly shaped to begin with and also to compensate where more narrow strips are rolled.

Fig. 9 is a cross section of the rolling mill showing the same principle, as shown in Figs. 6, 7 and 8, but applied to a mill where the working rolls l2 are supported by intermediate rolls 22, said intermediate rolls 22 being in their turn sup ported by backing rings II, in such a way that each supporting roll 22 is backed by two series of backing rolls mounted in the mill housing, in the same way as shown in the previous flgures. Said intermediate rolls 22 are specially useful when it is desired to preserve the polish of the working rolls. With such a disposition, I realize the compensation in making slots, as 28 in a supporting beam, as ll. Said slot has its depth increased when approaching the ends of the supporting beam and thus gives the desired compensatge eflect to the sag of the supporting It is evident that the feature of realizing the compensation of the roll deflection by means applied to the mill housing may certainly be combined to acompensative feature brought on to the working or supporting rolls, as shown on Figs. 1-7. At all events, the sizes of said compensative features must be strictly proportioned to the condition in which the rolling operation is to be performed. It is to be remarked that I can use the different mentioned compensative features in combination or separately, without departing from the spirit of my invention. In practice, the deflections are so small, that in most of the cases it is quite suflicient to apply my compensating means to one working roll or to one set of supporting rolls, or to one beam only, so as to completely compensate sags produced by the roll pressure.

It is to be remarked that I described my invention, as applied to turning rolls of a rolling mill, whereas it can be as well used with stationary rolls or dies and in all cases where it is required to compensate deflection caused by variable pressure of-the work on the working means.

Having thus described the nature of my invention. what I claim is:

1. In a mill for rolling flat'stock, working and intermediate rolls, supporting beams, and backing elements for said intermediate rolls situated in channels provided in said supporting beams, said supporting beams havingslots therein parallel to said rolls and of a depth gradually increasing toward the extremities of said supporting beams, saidslots so disposed as to permit an additional sag of said backing elements in a direction transverse to said beams, said sag increasing with increasing depth or said slots.

2. A sag compensating roll for supporting a working roll, said compensating roll having throughout its length an axial hole, said axial hole gradually increasing in diameter toward the ends of said roll, in order to increase the flexibility thereof in such a way as to produce a sa! equal and opposite to the spring of the mill.

3. In a mill for rolling metal sectionsoi small thickness in relation to their width, and in which the rolls tend to have a non-uniform elongating power in the direction of their length chiefly because of a progressive increase in their deflection from their ends to their centers due to elastic deflections of the mill components under' the working stresses, means for substantially compensating this tendency for non-uniformity in elongating power, comprising at least one mill component having the property of distortion under working stresses as distinguished from deflection, which distortion progressively increases from the roll centers toward their ends whereby the resultant elongating power of the mill is substantially uniform across the width of the section for all roll pressures, said distortion constituting a change in the cross section of said component in a plane taken through the millperpendicular to the axes of the working rolls thereof.

4. Ina mill for rolling working pieces with substantially flat cross sections where the working rolls tend to lose a portion of their reducing power progressively from the ends of the rolls toward their centers due to normal deflection of mill components, working rolls and other mill components, and means for compensating for the normal deflection oi said rolls, saidmeans comprising at least one mill component having distortion of cross section in a plane perpendicular to the axes of said working rolls, said distortion varying in inverse ratio to the said normal deflection, the total distortion being so proportioned that for all cross sections of the piece the sum of normal deflection and distortion is substantially a constant, at all roll pressures. I 5. Apparatus as claimed in claim 4 in which said mill component having distortion is/ a roll. 6. Apparatus as claimed in claim 4 in'which said mill component having distortion is a roll having a core and an outer shell, and a section intermediate said core and outer shell having said distortion characteristics. 7. Apparatus as claimed in claim 4 in which said mill component having distortion is a roll having a core and an outer shell, and a section intermediate said core and outer shell having said distortion characteristics, and comprising a layer of metal of diflerent compressibility than said core and shell, said layer being varied as to its thickness longitudinally of said roll.

8. Apparatus as claimed in claim 4 in which said mill component having distortion is a roll having a core and an outer shell, and a section intermediate said core and outer shell having said distortion characteristics, and comprising a layer of metal of different compressibility than said core and shell, said layer being varied as to its thickness longitudinally of said roll, and acting to permit a progressive flattening of said shell under stress toward the ends of said roll, whereby the elongating power of said roll is diminished towards its ends.

9. Apparatus as claimed in claim 4 in which said mill component is a roll having a portion of its body intermediate the outer surface and inner portions provided with interspaced holes of varying length to increase the compressibility of the portion of the body of said roll which contains said holes.

10. Apparatus as claimed in claim4 in which said mill component having distortion is a roll, and in which said roll is perforated end to end with a perforation increasing in diameter from the center of theroll towards its ends, whereby said roll is permitted to distort under stress to varying oval cross sections. 7

11. Apparatus as claimed in claim 4 in which the mill components include beams, and working rolls supported throughout their length upon said beams by means of intermediate members. engaged in supporting portions of said beams terminating laterally in lips, and in which at least one of said beams constitutes the component having said distortion, said beam having means permitting variable springing of said supporting pertions of said beams with relation to other portions of said beams.

12. Apparatus as claimed in claim 4 in which the mill components include beams, and working rolls supported throughout their length upon said beams by means of intermediate members engaged in supporting portions of said beams terminating laterally in lips, and in which at least oneof said beams constitutes the component having said distortion, said distortion residing in soontour of saidiips whichpermitssaidlipstospring under stress with relation to the remaining portions ofthebeam, to a greaterextenttowardthe ends of said beam than at the center thereof.

TADIUBZ